Clarkson Valley, MO, USA
N96MP
BELL 206B
During the flight that preceded the accident flight, the pilot stated to one of the two officers aboard the helicopter that he would not be able to fly for as long as normal because he needed to obtain fuel. Upon completion of the observation flight, the pilot returned to the police department and shut down the helicopter to allow the two officers to exit. The pilot then restarted the helicopter and departed en route to an airport where he could refuel the helicopter. A witness near the accident site stated that he heard the helicopter’s engine sputter and stop and saw the main rotor separate from the helicopter. The helicopter entered an uncontrolled descent and impacted terrain. Postaccident examination of the helicopter revealed that there was no usable fuel on board and that the main rotor mast separated as a result of overload due to mast bumping (main rotor hub to rotor mast contact). No preimpact mechanical anomalies that would have precluded normal operation of the helicopter were noted. Mast bumping typically results from a low-G flight condition caused by the pilot pushing the cyclic control forward abruptly from either straight-and-level flight or after a climb. Pushing the cyclic forward abruptly is contrary to the appropriate actions for entering an autorotation, which are lowering the collective pitch control to the full down position, adding antitorque pedal as needed to maintain heading, and applying cyclic as needed to maintain proper airspeed. Review of the pilot’s medical records indicated that he had a history of depression, anxiety, and obstructive sleep apnea. Each of these conditions had been documented and treated since 2007, and none were reported to the Federal Aviation Administration (FAA) on the pilot’s airman medical application in 2010 or earlier. Any of these conditions may have disqualified the pilot from obtaining an airman’s medical certificate. Postmortem toxicological testing indicated that the pilot was taking alprazolam, an anti-anxiety medication, and venlafaxine, an anti-depressant. Alprazolam is one of a class of drugs which may worsen obstructive sleep apnea, and venlafaxine can cause fatigue and dizziness. The fact that the blood level of venlafaxine found was higher than normal therapeutic levels makes it more likely that the side effect of dizziness occurred and impaired the pilot’s performance.
HISTORY OF FLIGHT On October 15, 2010, at 1110 central daylight time, a Bell 206B, N96MP, operated by the Missouri State Highway Patrol (MSHP), impacted terrain near Clarkson Valley, Missouri. Visual meteorological conditions prevailed at the time of the accident. The 14 Code of Federal Regulations Part 91 flight was not operating on a flight plan. The private pilot, who was the sole occupant, was fatally injured. The flight last departed from Arnold, Missouri, about 1053 and was en route to Spirit of St. Louis Airport (SUS), St. Louis, Missouri. Two MSHP Troopers arrived at the Arnold Police Department, located in Arnold, Missouri, about 0845, to fly with the pilot on a speed enforcement operation in the accident helicopter. They saw the helicopter approach from the east and land in a field just south of the police department shortly before 0900. Shortly after 0900, the flight departed from the field and headed towards interstate 55. The trooper who was seated in the front seat stated that while the helicopter was en route, he observed that the fuel gauge was “slightly above 25.” The trooper stated that the pilot pointed to the altimeter and said that the altitude was 1,500 feet. The trooper also stated that the pilot said that he would not be able to “stay up as long as normal” because he would have to obtain fuel before his next flight in Franklin County at 1200. After over an hour of flying, the pilot informed the troopers that he would perform an additional speed enforcement, which was completed about two minutes later. While returning to the Arnold Police Department, the trooper in the front seat asked the pilot how long it took to fly from the Arnold Police Department to St. Louis; the pilot replied that it took about 10 minutes. When the helicopter landed, the trooper in the front seat noticed that the fuel gauge indicated “half way between E and 25.” The pilot shut down the helicopter, and the two troopers aboard exited. The front seat trooper stated, that throughout the flight, the pilot made no statements about the helicopter not running “properly.” The front seat trooper noticed “no strange or unusual noises or actions” from the helicopter when it took off for SUS. A witness near the accident site stated that the helicopter was flying from right to left. He heard the noise of the engine “sputter” and then “stop.” The rotor had separated from the helicopter and they both descended. The helicopter fuselage was “gyrating wildly” and “seemed out of control.” PERSONNEL INFORMATION The pilot, age 47, was appointed to the MSHP on August 1, 1993. On October 3, 2003, he was issued a private pilot certificate with a single-engine airplane rating. On October 19, 2003, he became a pilot for the MSHP and was based at SUS. He was later issued the following ratings: airplane multiengine land, instrument airplane, and helicopter. He accumulated a total flight time of 2,607 hours, of which 820 hours were in the make and model of the accident helicopter. Pilot logbook records show that the pilot received his last Part 61.107 flight review following the completion and issuance of a multiengine airplane rating on his pilot certificate. The training and rating issuance was from April 7 to April 9, 2009. On June 2, 2010, the pilot completed his last Bell 206B training at Bell Helicopter Training Academy, Ft. Worth, Texas, using a Bell 206B. The training was refresher training that had a flight duration of 1.5 hours and no ground training. The training included Bell 206B emergency procedures. The pilot had no Federal Aviation Administration (FAA) record of previous accidents, incidents, or enforcement actions. AIRCRAFT INFORMATION The 1981 Bell 206B, serial number 3377, helicopter was operated by and registered to the MSHP. The helicopter was powered by an Allison 250-C20B, serial number CAE-832009, engine. The helicopter was last inspected during a 100-hour/300-hour/annual inspection dated May 7, 2010, at a total time of 11,185.4 hours and an hour meter of 2,133.4 hours. The engine was last inspected during a 100/300-hour inspection dated May 7, 2010, at a total time of 11,185.4 hours and an hour meter of 2,133.4 hours. The total airframe time at the time of the accident was 11,254.5 hours. METEOROLOGICAL INFORMATION The SUS automated weather observing system recorded at 1054: wind – 240 degrees at 8 knots, visibility – 10 statute miles, weather phenomena – clear, temperature – 16 degrees Celsius, dew point – 3 degrees Celsius, altimeter setting – 30.11 inches of mercury. WRECKAGE AND IMPACT INFORMATION The accident site was located about 3 nautical miles southeast of SUS and at an elevation of about 632 feet. The debris path was about 600 feet in length and oriented along a south-southeast (SSE)/north-northwest (NNW) heading. The debris path contained blue and white colored paint chips that were near the SSE area of the debris path and extended to about 400 feet from the helicopter fuselage, which was near the NNW edge of the debris path. The paint chips were consistent in color with the exterior of the helicopter. The main rotor with the rotor hub attached was located about 50 feet SSE of the helicopter fuselage. The fuselage was on its left side with the tail boom and tail rotor attached. The area surrounding the main wreckage did not contain evidence consistent with fuel spillage. Examination of the main rotor revealed that one of the two attached rotor blades exhibited blue marks consistent with the color of the helicopter. The blue marks were located in a spanwise direction of about 13 feet from the hub. The areas of separation of the pitch change links were consistent with overstress. The tail boom was twisted with the tail rotor intact. There was gouging on the top portion of the tail boom near the horizontal stabilizer, about 13 feet from the main rotor hub. There was no circumferential scoring on the tail rotor drive shaft and/or covering. No binding was noted when the tail rotor was rotated and the pitch change links were manipulated using hand pressure. The short shaft was deformed into the engine exhaust and did not display circumferential scoring. Examination of the fuel system revealed that about 3 quarts of liquid consistent with JET A aviation fuel was present in the fuel tank bladder. The fuel shut off valve was in the open position, and it would open and close when a 24-volt electrical source was applied. The low fuel switch was also tested and was functional. The fuel float arm was intact and was moved by hand without restriction. The airframe fuel filter (volume of the fuel filter container was about 20 ounces) contained about 1 ounce of liquid consistent with JET A. The fuel line leading to the inlet of the engine driven fuel pump contained 2 drops of liquid consistent with JET A. The fuel lines were intact. Examination of the flight control system confirmed flight control continuity. MEDICAL AND PATHOLOGICAL INFORMATION The pilot’s medical information was reviewed by the Medical Officer for the National Transportation Safety Board. A review of the pilot’s FAA Aerospace Medical Certification Division records revealed that his last application for a Second Class Airman’s Medical Certificate was made on May 27, 2010. The pilot answered “No” to the question “Do you take any medications?” He answered “No” to the question “mental disorders of any sort; depression, anxiety, etc.” Medical issues reported by the pilot were a kidney stone in 1987, hay fever and allergies to “cats and grass clippings.” The pilot’s aviation medical examiner found no issues on physical exam or in the patient’s clinical history that would have disqualified the pilot for an Airman’s Medical Certificate. The Second Class medical certificate was awarded on May 27, 2010. An autopsy of the pilot was performed by the St. Louis County Medical Examiner’s Office, on October 16, 2010, revealed that death resulted from multiple blunt injuries to the head, neck, chest, abdomen, and all extremities. The FAA Final Forensic Toxicology Fatal Accident Report reported the following: No ethanol detected in urine Alpha-hydroxyalprazolam not detected in blood 0.204 (ug/mL, ug/g) Alpha-hydroxyalprazolam detected in urine 0.134 (ug/ml, ug/g) Alprazolam detected in urine Alprazolam not detected in blood 0.961 (ug/mL, ug/g) Desmethylvenlafaxine (O-) detected in blood Desmethylvenlafaxine (O-) detected in urine Naproxen detected in urine 0.547 (ug/ml, ug/g) Venlafaxine detected in blood Venlafaxine detected in urine TESTS AND RESEARCH Engine Examination: The engine underwent a disassembly examination at Rolls Royce, Indianapolis, Indiana, under the supervision of an FAA inspector from the Indianapolis Flight Standards District Office. The inspector reported that the compressor halves were removed, and one half showed a rub mark on the lining material that extended 40-45 degrees of rotation. Compressor blade bending was also noted. The damage was consistent with engine rotation at the time of impact. The number 1 bearing rotated freely after removal of the housing, which had sustained impact damage. The centrifugal compressor shroud was removed and rub marks were noted on about 180 degrees of the shroud. The turbine section was separated at the power turbine split line. The number 3 and 4 turbine wheels rotated freely. There were no rotational marks in the number 3 or 4 blade paths. The number 1 and 2 turbine wheels would rotate but not freely, which was consistent with crush damage at the aft end of the turbine section. There were no rotation marks on the number 2 wheel blade path. All of the fuel nozzle spray holes appeared to be open. There was little or no fuel in any of the fuel lines from the fuel control to the fuel nozzle. Component Examination: The following components were sent to Bell Helicopter, Hurst, Texas, for examination under the supervision of an FAA COS Specialist from the Aircraft Certification Service, Rotorcraft Directorate, Fort Worth, Texas: mast section, yoke, sprag clutch, and coupling. The mast section was fractured well above the shoulder on the mast. The mast was elongated and possessed slight bending on the examined section. A fracture immediately below the splined portion of the trunion exhibited a shear from overload feature. The mast at the fracture was elongated. The mast was twisted at the spline. The yoke and torsion-tension straps were examined and no anomalies were noted. The sprag clutch housing exhibited impact damage. The clutch rotated freely and was observed to clutch and declutch. Witness marks present on the shaft were consistent with impact damage. The coupling was bound internally due to impact damage, which precluded disassembly. No anomalies were noted. The Rotorcraft Flying Handbook (FAA-H-8083-21), Chapter 11, Low G Conditions and Mast Bumping, states, in part, that “pushing the cyclic control forward abruptly from either straight-and-level flight or after a climb can put the helicopter into a low G flight condition.” Figure 11-9, states, “In a low G condition, improper corrective action could lead to the main rotor hub contacting the rotor mast. The contact with the mast becomes more violent with each successive flapping motion. This, in turn, creates a greater flapping displacement. The result could be a severely damaged rotor mast, or the main rotor system could separate from the helicopter.” MSHP Operating Procedures The MSHP Aircraft Operations Standard Operating Procedures (Revision 7-2006), II. Policy and Procedures, F. Use of Intoxicants and Drugs, paragraphs 2a and b, states: “Certain drugs in common use have a marked effect on the nervous system, which is temporarily detrimental to flight crew’s flying ability. Crewmembers will ask their doctor if any prescribed drug, or any nonprescription medications they are taking will affect their ability to function as a pilot. Any pilot whose ability to pilot an aircraft is affected by a drug will not operate patrol aircraft.” “Crew members are authorized and expected to ground themselves when the possibility of drug side effects exist or when they sense that their physical or mental condition might affect their ability to perform flight crew duties. In such cases, a flight surgeon will be consulted and an estimated availability date for resumption of flying duties will be provided to the member’s supervisor and to the Director of Aircraft.” III. Duties, Responsibilities, and Qualifications, H. Flight Crew Qualifications – General, paragraph 2, states: “All pilots will possess at least a current second-class medical certificate, which has been issued within the preceding twelve (12) months. No pilot will be assigned any flight duties during a period of a known physical deficiency that would render him unable to pass the examination for this certificate.” The MSHP party representative stated that the Troop C Command Staff, the Director of the Aircraft Division, and all personnel in the pilot’s chain of command had no knowledge of the pilot’s use of the medications listed in the FAA Final Forensic Toxicology Fatal Accident Report or his medical condition that would have been associated with their use.
The total loss of engine power due to fuel exhaustion, which resulted from the pilot's inadequate preflight planning and decision-making, and his improper control inputs following the loss of engine power, which resulted in mast bumping and separation of the main rotor. Contributing to the accident was the pilot's improper judgment in acting as a pilot with disqualifying medical conditions.
Source: NTSB Aviation Accident Database
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